docstr: Try to get answer from known external libraries.
          
docstr_tok: ["Try","to","get","answer","from","known","external","libraries","."]
code: def external_answer(
      self, *sequences: Sequence[object]
  ) -> float | None:
      """Try to get answer from known external libraries."""
      # if this feature disabled
      if not getattr(self, "external", False):
          return None
      # all external libs don't support test_func
      test_func = getattr(self, "test_func", self._ident)
      if test_func is not self._ident:
          return None
      # try to get external libs for algorithm
      libs = libraries.get_libs(self.__class__.__name__)
      for lib in libs:
          # if conditions not satisfied
          if not lib.check_conditions(self, *sequences):
              continue
          # if library is not installed yet
          func = lib.get_function()
          if func is None:
              continue
          prepared_sequences = lib.prepare(*sequences)
          # fail side libraries silently and try next libs
          with suppress(Exception):
              return func(*prepared_sequences)
      return None
  
imports: from __future__ import annotations
  from collections import Counter
  from contextlib import suppress
  from typing import Sequence, TypeVar
  from ..libraries import prototype
  from ..utils import find_ngrams
label_desc: Use image node_id 8 for calling the Base obj's underlying member method code with example usage: obj.external_answer() and returns: None, None, None, func